从零开始学Java-Day05

测试break和continue

package cn.tedu.review;

import java.util.Scanner;

//本类用于测试break和continue
public class TestBreakAndContinue {
   public static void main(String[] args) {
      /*
       * 加了continue可以提高效率，
       * break 和 continue后面不可以直接加代码
       */
      Scanner scan = new Scanner(System.in);
      for (int i = 0; i < 10; i++) {
         System.out.println("请输入数字：");
         int num = scan.nextInt();
         if (num == 88) {
            System.out.println("猜对了");
            break;
         }else {
            System.out.println("猜错了！还剩下" + (10-i) + "次机会");
         }
      }
      
      
      scan.close();
      
   }
}

while 和 do - while

package cn.tedu.review;


import java.util.Random;
import java.util.Scanner;

//本类用于while 和 dowhile循环
public class TestWhile_dowhile {
   public static void main(String[] args) {
      Scanner scan = new Scanner(System.in);
      int n = creatNum();
      //System.out.println(n);
      while (true) {//死循环，需要设置程序的出口
         System.out.println("输入一个数");
         int num = scan.nextInt();
         if (num == n) {
            System.out.println("猜对了！");
            break;
         }else if (num > n) {
            System.out.println("大了");
         }else {
            System.out.println("小了");
         }
      }
      scan.close();
   }
   

   public static int creatNum() {
      //100以内的随机整数
      int num = new Random().nextInt(10);
      return num;
   }
}

数组

package cn.tedu.array;

//用于数组的遍历
public class TestArrayExec {
   public static void main(String[] args) {
      int[] months = {31,28,31,30,31,30,31,31,30,31,30,31};
      for (int i = 0; i < months.length; i++) {
         System.out.println(i + 1 + "月: " + months[i] + "天");
      }
   }
}

int[] a = new int[10];

变量a存放的是new int[10]的地址！！！

package cn.tedu.array;

import java.util.Arrays;

//此类用于练习数组的创建
public class TestCreatArrary {
   public static void main(String[] args) {
      int[] a = new int[5];//动态创建
      //静态创建
      int[] b = new int[]{1,2,3,4,5};
      int[] c = {1,2,3,4,5};
      char[] ch1 = {'a','b','c','d'};
      char[] ch2 = new char[] {'1','s','3','h'};
      //动态创建
      /**
       * 通过数组下标操作数组中的元素
       * 从0开始
       * 最大长度 = 数组长度 - 1
       */
      char[] ch3 = new char[5];
      ch3[0] = 'a';
      ch3[1] = 'b';
      ch3[2] = 'c';
      ch3[3] = 'd';
      ch3[4] = 'e';
      //打印数组
      /**
       * char类型底层做了处理，可以直接打印数组中的具体元素内容
       * 除了char意外的类型的数组，想要打印数组元素
       * 需要使用数组的工具类Arrays.toString(数组名)方法
       * 注意：Arrays使用是的工具包:Java.util.Arrays
       */
      System.out.println(Arrays.toString(a));
      System.out.println(Arrays.toString(b));
      System.out.println(Arrays.toString(c));
      System.out.println(Arrays.toString(ch1));
      System.out.println(Arrays.toString(ch2));
      System.out.println(Arrays.toString(ch3));
      
      System.out.println((a));
      System.out.println((b));
      System.out.println((c));
      System.out.println((ch1));
      System.out.println((ch2));
      System.out.println((ch3));
      
      String[] s = {"emt", "486", "lm"};
      System.out.println(s);
      //查看数组的长度-数组元素的个数（legenth）
      System.out.println(a.length);
      System.out.println(b.length);
      System.out.println(c.length);
      System.out.println(ch1.length);
      System.out.println("emt".toCharArray());
      
      
   }
}